Effective methods for the recovery and/or separation of particular ions such as platinum, ruthenium, palladium, copper, osmium, gold, silver, and mercury ions in either cation or complex anion form from solutions thereof, admixed with chelating agents and/or other ions which may be present, represent a real need in modern technology. As specific examples, efficient and economical separation of (1) small amounts of Pt, Pd, Au, Ag, Os, Cu, and/or Ru from Rh and/or Ir concentrates; (2) separation of Pt, Pd, Au, Ag, and/or Ru from solutions containing large amounts of base metals; and (3) separation of Cu and/or Hg as toxic wastes from acidic solutions, all represent real separation needs with presently either unsatisfactory technologies for their accomplishment, or for which more economical technologies are desired. These ions are often present at low concentrations in solutions containing other ions at much greater concentrations. Hence, there is a real need for a process to selectively concentrate and recover these ions.
It, is known that molecules containing both the thioether and/or thiol sulfur atoms, as well as amine nitrogen atoms, show strong and somewhat selective interactions with Pt, Pd, Au, Ag, Os, Cu, Ru, and Hg ions under acidic conditions. These molecules also interact with a variety of base metal ions under nonacidic conditions. The synthesis and use of molecules containing both thioether and/or thiol sulfur atoms, as well as simple amine nitrogen atom(s), covalently bonded to inorganic solid supports has been previously described by Tarbet et. al. in copending patent application Ser. No. 7/236,763, filed Aug. 26, 1988 and now U.S. Pat. No. 5,071,819 titled "Sulfur and Nitrogen Containing Hydrocarbons and Process of Using Same in Separating Desired Ions From Solutions Thereof," and in a pending continuation-in-part application Ser. No. 7/542,013, filed Jun. 22, 1990 and now U.S. Pat. No. 5,084,430 and also in a pending divisional application Ser. No. 7/545,209, filed Jun. 28, 1990. Only simple amine nitrogen atoms are disclosed in the pending Tarbet et al. patent applications. The synthesis and use of simple monothioether-aniline moieties covalently bonded to silica gel have been reported by T. Seshadri et al. in "Silica-Immobilized2-[(2-(triethoxysilyl)-ethyl)thio]aniline as a Selective Sorbent for the Separation and Preconcentration of Palladium," Anal. Chem, 60, 47-52 (1988). These molecules described by Seshadri et. al. have reduced capacities for all of the desired ions of current interest, except palladium. The kinetics of interaction with several of the ions are quite slow, and the loss of interactive strength with increasing acidity above 0.1M acid is also extensive for the ions of interest except palladium. The effectiveness of these materials with palladium in HCl matrices &gt;5M has not been studied and a small potential for degradation with increasing acidity was also noted. Finally, neither Os nor Ru could be eluted in any degree from these materials. The lower stability of these aniline based bound ligands is due in part to both the use of the weaker binding aniline nitrogen and aromatic thiol sulfur donor atoms.
The products and processes described in the present invention overcome virtually all of the difficulties of the related materials described above.